Collaborative composition is an established method within music education, but it is a relatively rare phenomenon between composers of large-scale musical works. This research explores collaborative composition in a professional context and highlights the potential and value of its inclusion in specialist composition training at a tertiary level. The paper explores approaches, processes and outcomes arising from collaborative composition through reflection on a large-ensemble collaborative work, Interpolations, composed by participant-researchers' Johannes Luebbers and Paul Williamson. The participant-researchers' background as jazz improvisers emerged as a point of significance and was observed to fundamentally impact the collaborative process. Listening and signifying are identified by Monson as integral to the interactive exchanges between jazz improvisers, which extended into the collaborative composition process. This was given the term 'Jazz Improvisers Collaborative Cycle' (JICC), reflecting the tacit skills jazz improvisers bring to a collaborative relationship. The composers were struck by the refreshing and inspiring nature of working collaboratively, the unexpected and complementary ideas and materials, and the value of a constant sounding board that enabled them to formulate, develop and refine ideas. This project suggests collaborative composition as an alternative model that would be valuable for further exploration within education and professional communities.